The present invention relates to a surgical device for use in ophthalmic surgery, and in particular to a retraction member for use in eye surgery of a living being for retraction of the iris.
Retraction members typically include an elongated body portion with a substantially hook-shaped end for retracting the iris, and a fixation element slideably mounted on the body portion for securing the retraction member in place when the body portion is inserted with its hook-shaped end into the anterior chamber through a suitable incision made in the cornea.
It is well known that adequate dilatation of the pupil of the eye is essential during e.g. cataract surgery. In particular, for removal of a cataract, the surgical procedure in the posterior section as well as anterior section of the eye requires a sufficiently large and constant viewing range for the surgeon. Generally, the dilatation of the pupil is effected through administration of pharmaceuticals. However, on occasions, the use of pharmaceuticals is insufficient to attain the desired dilatation so that the use of surgical instruments for retracting the iris is proposed, e.g. application of one or more suitably spaced iris retractors which attach to the iris to pull it outwardly for enlarging the opening of the pupil. The individual iris retractors are inserted into the anterior chamber of the eye through an incision in the cornea and suitably fixed in tight manner by the fixation element at the outer contour of the eye. After surgery, the iris retractor is released from the iris and withdrawn from the anterior chamber of the eye.
European Pat. No. 0 653 197 describes an iris retractor for use in the ophthalmic surgery, with the iris retractor having a body portion formed at one end with a hook-shaped engagement part for insertion into the anterior chamber of the eye and withdrawal of the iris. A plate-shaped fixation element is slideably mounted to the body portion to hold the body portion in place in the region of the transition area from the cornea to the sclera. The iris retractor is inserted into the anterior chamber via an incision in the cornea and withdrawn after conclusion of the surgical procedure.
U.S. Pat. No. 5,716,328 describes an iris retractor which includes an elongated body portion of flexible material for insertion through an incision in the eye to retract the iris, with the body portion including two parallel shafts secured to each other along a common longitudinal edge wherein each shaft has at least one end formed with a hook-shaped member. The shafts of the body portion are so joined together that the hook-shaped members diverge from the longitudinal edge downward at an angle to one another to exhibit a xcex9-shaped configuration, to thereby cover a widest possible range of the iris.
The use of such iris retractors for ophthalmic surgery in the anterior or posterior eye sections suffers, however, shortcomings insofar as they require an incision which must be sized at least as wide as the entire width of the hook-shaped engagement part to prevent inadvertent, traumatic lacerations.
It is thus an object of the present invention to provide an improved iris retractor, obviating the afore-stated drawbacks.
In particular, it is an object of the present invention to provide an improved retraction member which requires a comparably much smaller incision in the cornea for insertion into and withdrawal from the anterior chamber, and yet is able to substantially decrease a risk of injury to the eye, in particular during withdrawal of the retraction member.
These objects, and others which will become apparent hereinafter, are attained in accordance with the present invention by providing a retraction member having a hook-shaped engagement part for retracting the iris, with at least the engagement part of the retraction member being made of a deformable material with shape memory so that the retraction member is insertable into the anterior chamber with the engagement part in a substantially straight configuration, and subsequently the engagement part is able to recover its original hook-shaped configuration as a consequence of its material characteristics, to implement a retraction of the iris.
A retraction member according to the present invention requires only a relatively small incision in the cornea for insertion into or withdrawal from the anterior chamber, whereby the incision seals itself once the retraction member is withdrawn.
According to another feature of the present invention, the retraction member may be received in an elongate tube, which is insertable together with the engagement part of the retraction member in straight configuration into the anterior chamber, whereas a relative movement in axial direction between the tube and the retraction member clears the engagement part to allow recovery of its original hook-shaped configuration.
The retraction member may be a filament with shape memory and made over its entire length of flexible, polymeric material e.g. thermoplastic material such as polyamide, or metal, e.g. a nickel-titanium alloy. The engagement part is bendable into the straight configuration for insertion into the anterior chamber at a temperature below a temperature in the anterior chamber and recovers the hook-shaped configuration as a result of the elevated temperature in the anterior chamber. For example, the engagement part of the retraction member can be bent into the substantially straight configuration at a room temperature of about 18xc2x0 C. to 22xc2x0 C. for insertion into the anterior chamber, and recovers its original hook-shaped configuration when heated in the anterior chamber to a body temperature of the living being of about 35xc2x0 C. to 37xc2x0 C.
According to another feature of the present invention, the filament and/or the tube may be dyed with an optical warning color, preferably a color that contrasts a hue of the iris.
According to another feature of the present invention, a sleeve may be placed in the cornea for insertion of the retraction member, with the sleeve having a tubular member projecting into the anterior chamber and providing an abutment for upward bending of the engagement part when the retraction member is withdrawn.
Suitably, a fixation element is provided which is slideably secured to the retraction member or the tube and clampable in a desired position, whereby the fixation element has a disk-like configuration and is made of a caoutchouc mixture exhibiting an optical warning color.